=========================================
Empty bracket argument [bracket_argument]
=========================================

message([[]])

---
(source_file
 (normal_command
  (identifier)
  (argument_list
   (argument (bracket_argument))
  )
 )
 )

=======================================
One bracket argument [bracket_argument]
=======================================

message([[an argument]])

---
(source_file
 (normal_command
  (identifier)
  (argument_list
    (argument (bracket_argument))
  )
 )
 )

========================================
Two bracket arguments [bracket_argument]
========================================

message([[first argument]] [[second argument]])

---
(source_file
 (normal_command
  (identifier)
  (argument_list
    (argument (bracket_argument))
    (argument (bracket_argument))
  )
 )
 )

========================================================
Two bracket with two equals arguments [bracket_argument]
========================================================

message(
  [====[first argument]====]
  [====[second argument]====]
)

---
(source_file
 (normal_command
  (identifier)
  (argument_list
    (argument (bracket_argument))
    (argument (bracket_argument))
  )
 )
 )

===================================================
Bracket argument with line break [bracket_argument]
===================================================

message([[an argument
with line break
]])

---
(source_file
 (normal_command
  (identifier)
  (argument_list
    (argument (bracket_argument))
  )
 )
 )

=====================================================================================
Bracket argument with embedded brackets and equal signs line break [bracket_argument]
=====================================================================================

message([===[an argument
with line break ]==]
]===])

---
(source_file
 (normal_command
  (identifier)
  (argument_list
    (argument (bracket_argument))
  )
 )
 )